Machine element and method and apparatus for making same



A. J. FISHER. MACHINE ELEMENT AND METHOD AND APPARATUS FOR MAKING SAME.

APPLICA I91 1,365,029. I Patented Jan. 11,1921.

UNITED STATES PATENT OFFICE.

ALVA J. FISHER, OF EVANSTON, ILLINOIS, ASSIGNOR TO HURLEY MACHINECOMPANY, OF CHICAGO,- ILLINOIS, A CORPORATION OF ILLINOIS.

MACHINE ELEMENT AND METHOD AND APPARATUS FOR MAKING SAME.

Specification of Letters Patent.

Patented Jan. 11, 1921.

Application filed October 18, 1918. Serial No. 258,718.

T 0 all whom it may concern:

Be it known that I, ALVA J. FISHER, a citizen of the United States,residing at Evanston, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Machine Elements andMethods and Apparatus for Making the Same, of which the following is aspecification.

My invention relates to a machine element and method and apparatus formaking the same.

Gears intended to be mounted on shafts,

where accuracy of fit with the shaft is important, are usually machinemade, but it is desirable, for economy to cast such gears if possible,and in many classes of mechanisms cast gears will perform satisfactorilyin lieu of machine-cut gears. One of the objects of my invention is toprovide a cast gear that will accuratelyfit, and secure proper bearingupon its receptive shaft, with its shaft apertured initially so that notooling or drilling of the shaft hole is necessary to con dition thegear for use.

Furthermore in many situations, a gear element may beneficially besupplemented with working surfaces at its end, such as clutchparts-either projections or indentations, the surfaces of which shouldbe hard, and an object of my invention is to provide a unitarygear-and-clutch element having hardened clutch surfaces.

A further object of my invention is to afford a simple and effectivemethod of casting such gears or unitary gear-and-clutch elements orkindred articles of manufacture, insuring the existence in the productof the characteristics above referred to and also to provide apparatusfor the simple and eflicient production of the gears by such method.

To these ends, and others that will become apparent to those skilled inthe art, from the following description, my invention consists in thenovel features of structure and method hereinafter more fully described,and claimed.

In the drawing Figure 1 is a perspective view showing the unitarygear-and-clutch element; Fig. 2 is a detail of a sleeve; Fig. 3 is adetail of a chill block and core; Fig. 4 is an elevation of a pattern;Fig. 5 shows a mold with pattern embedded therein; Fig.

6 shows the mold with the pattern removed and replaced by the chillblock, carrying a sleeve; and Fig. 7 shows, sectionally, completion ofthe casting operation.

The specific gear 10, shown in Fig. 1, is of a construction that I usein washing machine gearing, and is of the beveled type, provided withcrown clutch projections; but it will be understood that in the broaderaspects of my invention I do not limit myself in these matters ofdetail, as'my invention may be practised in the production of many formsof gear elements and clutch elements and other machine parts intended tomterfit with shafts and of character suitably produced by castingoperations.

In the particular article shown the hub 11 and beveled gear teeth 12that constitute, in the specific structure shown, the peripheral orradial working surfaces of the element may, for many uses, ordinarily beof the relatively soft quality of sand-cast metal, and in many instancesthey have unfinished surfaces, although for finer work :more or lesssurface machining may be desirable and obviously employed if necessary,with some consequent increase in expense. It is, however, usuallyimportant that the shaft hole 13 be accurately sized and centered, anddifiiculty in meeting this requirement is an important objection to thecasting of gears and other shaft-fitting articles with preformed shaftholes. Clutch elements, such as the lugs 14, may best be of hardermaterial than sand-cast iron or steel, but in many instances must beunitary with the ear element. I preferably fulfil both requlrements bychilling the clutch surfaces in such a unitary gear clutch element, asdiagrammatically suggested by the shading at 15. Fig. 7.

To meet the important requirement of shaft hole sizing, I mold axiallyin the gear or kindred element a sleeve 16 of the appropriate internaldiameter, such sleeve, as indicated in Fig. 2, being preferably a truecylinder pre-formed of relatively thin metal, drawn or rolled. Inpractice I have found that satisfactory and economical use may be madeof sleeves formed up of sheet steel into a seamed tube, the seam 17being closed by welding 18 only at the ends of the cylinder. Thesesleeves I am able to make very accurate in size, and of true cylindricalcontour, with minimum expense. The cylinder is preferably slightlyshorter than the full length of the shaft hole so that, in the castingoperation, the cast metal may overlie the cylinder inner ends, atcertain spots, or throughout the circumference of the sleeve, as themold configuration may provide. Thus in. the particular constructionshown the sleeve may be completely overlain by the cast metal lip 1.).as shown in Fig. 7 at its upper end, and at its lower end it is overlainat spots 20 by lips of the clutch projections 14.

In the production of such an article of manufacture. wherein it isrequisite that the sleeve shall accurately define the shaft holediameter, and shall be centered very accurately with respect to thegear-periphery or gear-toothed portion of the element, I employ theapparatus and method of production that I will now describe.

The pattern 21, shown in Fig. 4, is suitably shaped in its central zone22 to give the desired form to the gear teeth and hub. It is, however,supplemented by axially tapering projections 23 and 24 to form guidecavities in the sand. Such a pattern, placed in the sand as shown inFig. 5, produces a cavity that gives suitable guide extensions axiallybeyond the central Zone. The diagrammatic illustration and commonknowledge of the casting art are suitable to give adequate informationas to convenient construction and parting of the flask, etc., withoutspecific description. The corepiece '25, Fig. 3, having a stem 26 neatlyinterfitting with and supporting the sleeve 16 and pref erably toproject slightly above the upper end thereof, and having a lower chillblock 27 recessed as at 28 to give shape to the clutch projections 14 ofthe casting, and having axial guide extensions 29 and 30 identicallycorresponding to portions (or whole) of the pattern portions 23 and 24,is fitted in the fiask as shown in Fig. 6, with the sleeve in placethereon. It will be observed that the guidance of the parts 29 and 30 inidentically shaped portions of the mold cavity insures absoluteprecision in the centering and alinement and axial positioning of thesleeve with respect to the mold cavity.

When the mold cavity is metal-filled, as shown in Fig. 7, the castingobviously takes the requisite form (due shrinkage allowance in the toothdimensions being made in accordance with known skilful practice). Thechill block is effective in chilling the surfaces with which it contactsto harden the active surfaces 15 of the clutch projections 14, asheretofore referred to. The sleeve plays an important part in thematter. When it is invested with the molten metal its thinness enablesit to expand rapidly, and then to shrink sufliciently with the coolingmetal to resume substantially its original diameter, its cylinder-formmaking it strongly resist over-compression or reduction to a diameterless than its initial size. The sleeve ,gives the inner surface of thecompleted element a uniform and desirable texture and finish, and,importantly, it insures easy removability of the article from thecorepiece and without scoring or otherwise injuring the stem of thelatter.

It will be apparent that the method and apparatus described areavailable in casting of parts other than the gear-and-clutch elementdescribed, and while I have herein set forth the details of onesatisfactory practice and embodiment of my invention, it will beunderstood that I do not thereby limit myself to such details in thebroader aspect of my invention but that many changes and adaptations maybe made within the spirit of my invention and within the scope of theappended claims.

lVhat I claim is:

1. As an article of manufacture, a machine element comprising apre-formed, shaft-fitting sleeve and a metal body cast therearoundhaving, integrally, soft cast portions forming peripheral working surfaces and harder, chilled working surfaces at its end.

2. As an article of manufacture, a gear element comprising ashaft-fitting sleeve pre-formed of appropriate diameter, and a castmetal gear toothed body coaxial with and intimately engaging the sleeve,said element having integrally at an end chilled working surfaces harderthan the gearteeth.

3. As an article ofmanufacture, a combined gear-and-clutch elementhaving an axial shaft-fitting opening, peripheral teeth, and clutchsurfaces; comprising a preformed sleeve affording the axialshaft-receptive opening of predetermined diameter and. a metal body casttherearound affording soft cast teeth and chilled clutch surfaces.

4. As an article of manufacture, a combined beveled gear and crownclutch ele ment comprising a pre-formed sleeve affording a shaft-fittingopening, a body cast therearound having peripheral teeth and chilledcrown clutch surfaces, and portions of said cast material extendingradially inward beyond the outer periphery of the sleeve to retain thesame axially.

5. The method of making cast, shaft fitting machine elements whichconsists in supporting a pre-formed, shaft fitting sleeve upon a metalchill-block an integral portion of which enters the sleeve and a furtherportion of which constitutes a casting-shaping surface; inserting thesleeve and chill-block in a non-chilling mold affording a suitablecavity which will expose the shaping surface of the chill block, andcasting the element mes es upon and about the sleeve and in contact,throughout part oil? its surface, with the chill block.

6. The method of casting shaft-fitting machine elements, which consistsin preparing a molding cavity with opposed guide-extensions at its endsextraneous to the articleshaping surfaces of the cavity, supporting athin, pie-formed, shaftfitting sleeve snugly on a metallic core-piecethat extends beyond the sleeve and is shaped adjacent its ends to litthe opposite guide extensions of the mold, placing said sleeve-carryingcore-piece in the guiding cavity extensions and casting the machineelement around the sleeve.

7. The method of making a combined gear-and-clutch element whichconsists in forming in molding material a cavity for shaping peripheralportions of the article and having axial guide extensions, setting insaid cavity a corepiece having portions similar to and interfitting withthe guide extensions of the cavity and affording also a chill blocksurface defining an end portion of the molding surface, providing apreformed sleeve encircling and interfitting with an axial portion ofsaid corepiece, and casting said element around said sleeve.

ALVA J. FISHER.

